Inertia-operated switch



I 195-9 7 D. D. MILLER H 3, 71,661 INERTIA-OPERATED SWITCH Filed March 14, 1968 BY 0022042 Q [ZN/er Mai/4.7M

ATTORNEY United States Patent 3,471,661 INERTIA-OPERATED SWITCH Donald D. Miller, Saginaw, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Mar. 14, 1968, Ser. No. 713,157

Int. Cl. H01h 35/14 U.S. Cl. 200-61.48

ABSTRACT OF THE DISCLOSURE An electrical switch having a pair of spring biased normally open contacts maintained closed by a retaining arm member, rotatable about a pivot point, which is operable, upon the movement of an inertia weight, to open the contacts. A trigger pin secured to one end of a trigger arm, rotatable about another pivot point, engages a pawl on one end of the retaining arm member to maintain the retaining arm member in the position to close th switch contacts. Movement of the inertia weight will cause a cam followerpin secured to the opposite end of the trigger arm to follow either leg of a V-shaped cam surface of the inertia weight support member and rotate the trigger arm about its pivot point in a direction to release the trigger pin from the pawl of the retaining arm member thereby permitting the force of the contact spring bias to rotate the retaining arm member about its pivot point and open the switch contacts,

This invention relates to electrical switches and, more specifically, to inertia operated electrical switches.

Inertia operated switches are well known in the art, however, heretofore, switches of this type have been cumbersome and included may moving parts.

It is, therefore, an object of this invention to provide an improved inertia operated switch.

It is another object of this invention to provide an improved inertia operated switch having a minimum of moving parts.

In accordance with this invention, an inertia operated switch is provided wherein the associated spring biased normally open contacts are maintained in electrical contact by a cam surface on one end of a pivotally mounted retaining arm member which is locked in the position to maintain the contacts closed by a trigger pin, secured to one end of a pivotally mounted trigger arm, engaging a pawl on the other end thereof and are released to open upon the moveemnt of a weight secured to a resiliently suspended weight support member having a V-shaped cam surface in operative engagement with a cam follower pin on the other end of the trigger arm to rotate the trigger arm in a direction to move the trigger pin out of engagement with the retaining arm pawl.

For a better understanding of the present invention together with additional objects, advantages and features thereof, reference is made to the following description and accompanying drawing in which FIGURE 1 is a front view of the inertia operated switch of this invention and FIGURE 2 is a section view of FIGURE 1 taken along line 2-2 and looking in the direction of the arrows.

Referring to the figures of the drawing, wherein like elements have been given like characters of reference in the two figures, the inertia operated switch of this invention has a stationary electrical contact and a movable electrical contact 12 mounted upon a movable member 14 which is spring biased in a direction to open the contacts. With movable contact 12 in electrical engagement with stationary contact 10, an electrical circuit is established between conventional binding posts 15 and 16 1 Claim through movable member 14. Movable member 14 may be made of an electrically conductive spring material to provide the necessary spring bias in a direction to open the contacts, as shown in the drawing, or alternate conventional spring biased movable contact arrangements may be employed.

The mechanism of the switch of this invention may be enclosed within a suitable box like enclosure 18 having an access cover 20.

Resiliently suspended within the enclosure is a weight support member 22 having two V-shaped cam surfaces 24 and 25 to which is secured a weight 26. The weight support member is suspended in its reset position by reset springs 28 and 29 which may be secured to the enclosure 18 by any suitable method such as brazing or staking and which engage fixed pins 30 and 31, respectively, rigidly secured to the weight support member 22.

A retaining arm member 34, having a pawl on one end and a cam surface 36 on the other end, is mounted for rotation about pivot point 37 in such a manner that cam surface 36 is in engagement with movable member 14. Upon the rotation of retaining arm member 34 in a clockwise direction about pivot point 37, movable contact 12 is moved into electrical engagement with stationary contact 10 against the force of the spring bias of movable member 14.

A trigger arm member 40, having a trigger pin 41 on one end and a cam follower pin 42 on the other end, is mounted for rotation about pivot point 43. Trigger pin 41 is engageable with pawl 35 of retaining arm 34 upon the rotation of trigger arm 40 in a clockwise direction about pivot point 43 and cam follower pin 42 is in operative engagement with V-shaped cam surface 24 of weight support member 22. Trigger arm 40 is urged in a clockwise direction about pivot point 43 by spring 44 in a manner well known in the art. With trigger pin 41 in engagement with the pawl 35 of retaining arm 34, retaining arm 34 is locked in the position which will maintain movable contact 12 in electrical engagement with stationary contact 10 against the force of the spring bias of movable member 14.

Fixed pin 46, which is rigidly secured to the enclosure 18, is in operative engagement with the other V-shaped cam surface 25 of weight support member 22.

Extending through enclosur 18 is a reset arm 48 having a reset handle 49. Retaining arm member 34 may be rotated in either direction from outside enclosure 18 through reset handle 49 and reset arm 48.

The switch is operated by movement of weight 26. Any movement of weight 26 either rotates or translates Weight support member 22 Which results in either the rotation thereof about fixed pin 46 or cam follower pin 42 or the translation thereof along both fixed pin 46 and can follower pin 42. In either event, cam follower pin 42 follows either one leg of cam surface 24 to rotate trigger arm 40 in a counterclockwise direction about pivot point 43 which rotates trigger pin 41 out of engagement with pawl 35 to release retaining arm 34. With retaining arm 34 thus released, the spring bias force of movable member 14, acting through cam surface 36, rotates retaining arm member 34 in a counterclockwise direction about pivot point 37 and opens the electrical contacts 10 and 12 to interrupt the electrical circuit between binding posts 15 and 16.

After the switch has operated, reset springs 28 and 29 return weight support member 22 and the attached weight 26 to the reset suspended position and reset handle 49 may be operated to revolve retaining arm member 34 in a clockwise direction about pivot point 37 until spring 44, biased to revolve trigger arm member 40 in a clockwise direction about pivot point 43, moves trigger pin 41 into engagement with pawl 35, thereby resetting the switch for the next operation.

While a preferred embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that various modifications and substitutions may be made without departing from the spirit of the invention.

I claim:

1. An inertia operated switch having a stationary electrical contact and a movable electrical contact mounted upon a movable member spring biased in a direction to open the electrical contacts comprising, a enclosure, a weight, a weight support member having two V-shaped cam surfaces resiliently suspended within said enclosure for movably supporting said weight which is secured thereto, a retaining arm member mounted for rotation about a first pivot point having a pawl on one end thereof and a cam surface on the other end thereof in engagement with said movable member upon which said movable contact is mounted for operating said movable contact into electrical engagement with said stationary contact against the force of said spring bias upon the rotation of said retaining arm member in a first direction about said first pivot point, a trigger arm member mounted for rotation about a second pivot point having a trigger pin secured to one end thereof engageable with said pawl on said retaining arm member for locking said retaining arm member in the position which will maintain said movable contact in electrical engagement with said stationary References Cited UNITED STATES PATENTS 2,671,832 3/1954 Hansard et a1. 200-6153 2,780,688 2/ 1957 Stec 200-61.52 2,885,505 5/ 1959 Mathisen 20061.53 2,981,809 4/1961 Van Horn 1 .00-61.52 X 2,986,614 5/ 1961 Minch 20061.5

FOREIGN PATENTS 263,217 1/ 1927 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner ROBERT A. VANDERHYE, Assistant Examiner US. Cl. X.R. 200-6152, 61.5 

